GREELEY, Colo. (CBS4) – A school in Greeley is asking parents to be more vigilant after a 10-year-old boy admitted to selling marijuana to other students on the playground and another student came to school with a marijuana edible candy bar.

Both incidents happened in one week.

School officials are now asking parents to pay attention to where they are keeping their recreational marijuana after the fourth graders brought the items to Monfort Elementary School in Greeley.

John Gates, director of safety for Weld County School District 6, said there were four students involved — three boys and a girl. The students were all 10.

Gates said the students faced tough discipline but not suspension or expulsion but would not provide specific details on their punishment.

One boy admitted to taking a small bite of the candy bar but he didn’t get sick, and a medical exam showed he didn’t suffer any harmful side effects.

Gates said the boys told them they got the pot from home. That marijuana appears to have been legally purchased by adults. The grandparents in two families apparently made the purchases. No charges are expected to be filed.

On Monday a student who was not involved told school officials about the pot selling on the playground and the next day a student tried to trade an edible for some of the student’s marijuana.

“It was the simple fact that we had adults that didn’t secure their marijuana,” Gates said of the grandparents, urging adults to take care with the drug. “That sure is concerning because this would have never happened had the marijuana not been so accessible to two 10-year-old boys.”

Monfort Elementary School principal Jennifer Sheldon sent home a letter to parents on Tuesday stating that even though it’s easier for adults to get marijuana, children potentially have greater access.

A portion of that letter reads: “We urge all parents, grandparents and anyone who cares for children to treat marijuana as you would prescription drugs, alcohol or even firearms. This drug is potentially lethal to children, and should always be kept under lock and key, away from young people.”